Types of Oracle Database Users

The types of users and their roles and responsibilities depend on the database site. A small site can have one database administrator who administers the database for application developers and users. A very large site can find it necessary to divide the duties of a database administrator among several people and among several areas of specialization.

Database Administrators

Each database requires at least one database administrator (DBA). An Oracle Database system can be large and can have many users. Therefore, database administration is sometimes not a one-person job, but a job for a group of DBAs who share responsibility.

A database administrator's responsibilities can include the following tasks:

Installing and upgrading the Oracle Database server and application tools

Allocating system storage and planning future storage requirements for the database system

Creating primary database storage structures (tablespaces) after application developers have designed an application

Creating primary objects (tables, views, indexes) once application developers have designed an application

Modifying the database structure, as necessary, from information given by application developers

Enrolling users and maintaining system security

Ensuring compliance with Oracle license agreements

Controlling and monitoring user access to the database

Monitoring and optimizing the performance of the database

Planning for backup and recovery of database information

Maintaining archived data on tape

Backing up and restoring the database

Contacting Oracle for technical support

Security Officers

In some cases, a site assigns one or more security officers to a database. A security officer enrolls users, controls and monitors user access to the database, and maintains system security. As a DBA, you might not be responsible for these duties if your site has a separate security officer. Please refer to Oracle Database Security Guide for information about the duties of security officers.

Network Administrators

Some sites have one or more network administrators. A network administrator, for example, administers Oracle networking products, such as Oracle Net Services. Please refer to Oracle Net Services Administrator's Guide for information about the duties of network administrators.

When upgrading to a new release, back up your existing production environment, both software and database, before installation. For information on preserving your existing production database, see Oracle Database Upgrade Guide.

Task 1: Evaluate the Database Server Hardware

Evaluate how Oracle Database and its applications can best use the available computer resources. This evaluation should reveal the following information:

How many disk drives are available to the Oracle products

How many, if any, dedicated tape drives are available to Oracle products

How much memory is available to the instances of Oracle Database you will run (see your system configuration documentation)

Task 2: Install the Oracle Database Software

As the database administrator, you install the Oracle Database server software and any front-end tools and database applications that access the database. In some distributed processing installations, the database is controlled by a central computer (database server) and the database tools and applications are executed on remote computers (clients). In this case, you must also install the Oracle Net components necessary to connect the remote machines to the computer that executes Oracle Database.

Task 3: Plan the Database

As the database administrator, you must plan:

The logical storage structure of the database

The overall database design

A backup strategy for the database

It is important to plan how the logical storage structure of the database will affect system performance and various database management operations. For example, before creating any tablespaces for your database, you should know how many datafiles will make up the tablespace, what type of information will be stored in each tablespace, and on which disk drives the datafiles will be physically stored. When planning the overall logical storage of the database structure, take into account the effects that this structure will have when the database is actually created and running. Consider how the logical storage structure of the database will affect:

The performance of the computer executing running Oracle Database

The performance of the database during data access operations

The efficiency of backup and recovery procedures for the database

Plan the relational design of the database objects and the storage characteristics for each of these objects. By planning the relationship between each object and its physical storage before creating it, you can directly affect the performance of the database as a unit. Be sure to plan for the growth of the database.

Task 4: Create and Open the Database

After you complete the database design, you can create the database and open it for normal use. You can create a database at installation time, using the Database Configuration Assistant, or you can supply your own scripts for creating a database.

Task 5: Back Up the Database

After you create the database structure, carry out the backup strategy you planned for the database. Create any additional redo log files, take the first full database backup (online or offline), and schedule future database backups at regular intervals.

Task 6: Enroll System Users

After you back up the database structure, you can enroll the users of the database in accordance with your Oracle license agreement, and grant appropriate privileges and roles to these users. Please refer to Chapter 22, " Managing Users and Securing the Database" for guidance in this task.

Task 7: Implement the Database Design

After you create and start the database, and enroll the system users, you can implement the planned logical structure database by creating all necessary tablespaces. When you have finished creating tablespaces, you can create the database objects.

Task 8: Back Up the Fully Functional Database

When the database is fully implemented, again back up the database. In addition to regularly scheduled backups, you should always back up your database immediately after implementing changes to the database structure.

Task 9: Tune Database Performance

Optimizing the performance of the database is one of your ongoing responsibilities as a DBA. Oracle Database provides a database resource management feature that helps you to control the allocation of resources among various user groups. The database resource manager is described in Chapter 24, " Using the Database Resource Manager".

Identifying Your Oracle Database Software Release

Because Oracle Database continues to evolve and can require maintenance, Oracle periodically produces new releases. Not all customers initially subscribe to a new release or require specific maintenance for their existing release. As a result, multiple releases of the product exist simultaneously.

As many as five numbers may be required to fully identify a release. The significance of these numbers is discussed in the sections that follow.

Release Number Format

To understand the release nomenclature used by Oracle, examine the following example of an Oracle Database server labeled "Release 10.1.0.1.0".

Starting with release 9.2, maintenance releases of Oracle Database are denoted by a change to the second digit of a release number. In previous releases, the third digit indicated a particular maintenance release.

Major Database Release Number

The first digit is the most general identifier. It represents a major new version of the software that contains significant new functionality.

Database Maintenance Release Number

The second digit represents a maintenance release level. Some new features may also be included.

Application Server Release Number

The third digit reflects the release level of the Oracle Application Server (OracleAS).

Component-Specific Release Number

The fourth digit identifies a release level specific to a component. Different components can have different numbers in this position depending upon, for example, component patch sets or interim releases.

Platform-Specific Release Number

The fifth digit identifies a platform-specific release. Usually this is a patch set. When different platforms require the equivalent patch set, this digit will be the same across the affected platforms.

Checking Your Current Release Number

To identify the release of Oracle Database that is currently installed and to see the release levels of other database components you are using, query the data dictionary view PRODUCT_COMPONENT_VERSION. A sample query follows. (You can also query the V$VERSION view to see component-level information.) Other product release levels may increment independent of the database server.

It is important to convey to Oracle the results of this query when you report problems with the software.

Database Administrator Security and Privileges

To perform the administrative tasks of an Oracle Database DBA, you need specific privileges within the database and possibly in the operating system of the server on which the database runs. Access to a database administrator's account should be tightly controlled.

The Database Administrator's Operating System Account

To perform many of the administrative duties for a database, you must be able to execute operating system commands. Depending on the operating system on which Oracle Database is running, you might need an operating system account or ID to gain access to the operating system. If so, your operating system account might require operating system privileges or access rights that other database users do not require (for example, to perform Oracle Database software installation). Although you do not need the Oracle Database files to be stored in your account, you should have access to them.

See Also:

Your operating system specific Oracle documentation. The method of creating the account of the database administrator is specific to the operating system.

Database Administrator Usernames

Two user accounts are automatically created when Oracle Database is installed:

SYS (default password: CHANGE_ON_INSTALL)

SYSTEM (default password: MANAGER)

Note:

Both Oracle Universal Installer (OUI) and Database Configuration Assistant (DBCA) now prompt for SYS and SYSTEM passwords and do not accept the default passwords "change_on_install" or "manager", respectively.

Create at least one additional administrative user and grant to that user an appropriate administrative role to use when performing daily administrative tasks. Do not use SYS and SYSTEM for these purposes.

Note Regarding Security Enhancements:

In this release of Oracle Database and in subsequent releases, several enhancements are being made to ensure the security of default database user accounts. You can find a security checklist for this release in Oracle Database Security Guide. Oracle recommends that you read this checklist and configure your database accordingly.

SYS

When you create an Oracle Database, the user SYS is automatically created and granted the DBA role.

All of the base tables and views for the database data dictionary are stored in the schema SYS. These base tables and views are critical for the operation of Oracle Database. To maintain the integrity of the data dictionary, tables in the SYS schema are manipulated only by the database. They should never be modified by any user or database administrator, and no one should create any tables in the schema of user SYS. (However, you can change the storage parameters of the data dictionary settings if necessary.)

Ensure that most database users are never able to connect to Oracle Database using the SYS account.

SYSTEM

When you create an Oracle Database, the user SYSTEM is also automatically created and granted the DBA role.

The SYSTEM username is used to create additional tables and views that display administrative information, and internal tables and views used by various Oracle Database options and tools. Never use the SYSTEM schema to store tables of interest to nonadministrative users.

The DBA Role

A predefined DBA role is automatically created with every Oracle Database installation. This role contains most database system privileges. Therefore, the DBA role should be granted only to actual database administrators.

Note:

The DBA role does not include the SYSDBA or SYSOPER system privileges. These are special administrative privileges that allow an administrator to perform basic database administration tasks, such as creating the database and instance startup and shutdown. These system privileges are discussed in "Administrative Privileges".

Database Administrator Authentication

As a DBA, you often perform special operations such as shutting down or starting up a database. Because only a DBA should perform these operations, the database administrator usernames require a secure authentication scheme.

Administrative Privileges

Administrative privileges that are required for an administrator to perform basic database operations are granted through two special system privileges, SYSDBA and SYSOPER. You must have one of these privileges granted to you, depending upon the level of authorization you require.

Note:

The SYSDBA and SYSOPER system privileges allow access to a database instance even when the database is not open. Control of these privileges is totally outside of the database itself.

The SYSDBA and SYSOPER privileges can also be thought of as types of connections that enable you to perform certain database operations for which privileges cannot be granted in any other fashion. For example, you if you have the SYSDBA privilege, you can connect to the database by specifying CONNECT AS SYSDBA.

SYSDBA and SYSOPER

The following operations are authorized by the SYSDBA and SYSOPER system privileges:

System Privilege

Operations Authorized

SYSDBA

Perform STARTUP and SHUTDOWN operations

ALTER DATABASE: open, mount, back up, or change character set

CREATE DATABASE

DROP DATABASE

CREATE SPFILE

ALTER DATABASE ARCHIVELOG

ALTER DATABASE RECOVER

Includes the RESTRICTED SESSION privilege

Effectively, this system privilege allows a user to connect as user SYS.

SYSOPER

Perform STARTUP and SHUTDOWN operations

CREATE SPFILE

ALTER DATABASE OPEN/MOUNT/BACKUP

ALTER DATABASE ARCHIVELOG

ALTER DATABASE RECOVER (Complete recovery only. Any form of incomplete recovery, such as UNTIL TIME|CHANGE|CANCEL|CONTROLFILE requires connecting as SYSDBA.)

Includes the RESTRICTED SESSION privilege

This privilege allows a user to perform basic operational tasks, but without the ability to look at user data.

The manner in which you are authorized to use these privileges depends upon the method of authentication that you use.

When you connect with SYSDBA or SYSOPER privileges, you connect with a default schema, not with the schema that is generally associated with your username. For SYSDBA this schema is SYS; for SYSOPER the schema is PUBLIC.

Connecting with Administrative Privileges: Example

This example illustrates that a user is assigned another schema (SYS) when connecting with the SYSDBA system privilege. Assume that the sample user oe has been granted the SYSDBA system privilege and has issued the following statements:

CONNECT oe/oe
CREATE TABLE admin_test(name VARCHAR2(20));

Later, user oe issues these statements:

CONNECT oe/oe AS SYSDBA
SELECT * FROM admin_test;

User oe now receives the following error:

ORA-00942: table or view does not exist

Having connected as SYSDBA, user oe now references the SYS schema, but the table was created in the oe schema.

Selecting an Authentication Method

The following methods are available for authenticating database administrators:

Operating system (OS) authentication

A password file

Notes:

These methods replace the CONNECT INTERNAL syntax provided with earlier versions of Oracle Database. CONNECT INTERNAL is no longer supported.

Operating system authentication takes precedence over password file authentication. If you meet the requirements for operating system authentication, then even if you use a password file, you will be authenticated by operating system authentication.

Your choice will be influenced by whether you intend to administer your database locally on the same machine where the database resides, or whether you intend to administer many different databases from a single remote client. Figure 1-2 illustrates the choices you have for database administrator authentication schemes.

If you are performing remote database administration, consult your Oracle Net documentation to determine whether you are using a secure connection. Most popular connection protocols, such as TCP/IP and DECnet, are not secure.

Nonsecure Remote Connections

To connect to Oracle Database as a privileged user over a nonsecure connection, you must be authenticated by a password file. When using password file authentication, the database uses a password file to keep track of database usernames that have been granted the SYSDBA or SYSOPER system privilege. This form of authentication is discussed in "Using Password File Authentication".

Local Connections and Secure Remote Connections

You can connect to Oracle Database as a privileged user over a local connection or a secure remote connection in two ways:

If the database has a password file and you have been granted the SYSDBA or SYSOPER system privilege, then you can connect and be authenticated by a password file.

If the server is not using a password file, or if you have not been granted SYSDBA or SYSOPER privileges and are therefore not in the password file, you can use operating system authentication. On most operating systems, authentication for database administrators involves placing the operating system username of the database administrator in a special group, generically referred to as OSDBA. Users in that group are granted SYSDBA privileges. A similar group, OSOPER, is used to grant SYSOPER privileges to users.

Using Operating System Authentication

This section describes how to authenticate an administrator using the operating system.

Preparing to Use Operating System Authentication

To enable operating system authentication of an administrative user:

Create an operating system account for the user.

Add the user to the OSDBA or OSOPER operating system defined groups.

Ensure that the initialization parameter, REMOTE_LOGIN_PASSWORDFILE, is set to NONE, the default.

Connecting Using Operating System Authentication

A user can be authenticated, enabled as an administrative user, and connected to a local database by typing one of the following SQL*Plus commands:

CONNECT / AS SYSDBA
CONNECT / AS SYSOPER

For a remote database connection over a secure connection, the user must also specify the net service name of the remote database:

OSDBA and OSOPER

Two special operating system groups control database administrator connections when using operating system authentication. These groups are generically referred to as OSDBA and OSOPER. The groups are created and assigned specific names as part of the database installation process. The specific names vary depending upon your operating system and are listed in the following table:

Operating System Group

UNIX

Windows

OSDBA

dba

ORA_DBA

OSOPER

oper

ORA_OPER

The default names assumed by the Oracle Universal Installer can be overridden. How you create the OSDBA and OSOPER groups is operating system specific.

Membership in the OSDBA or OSOPER group affects your connection to the database in the following ways:

If you are a member of the OSDBA group and you specify AS SYSDBA when you connect to the database, then you connect to the database with the SYSDBA system privilege.

If you are a member of the OSOPER group and you specify AS SYSOPER when you connect to the database, then you connect to the database with the SYSOPER system privilege.

If you are not a member of either of these operating system groups, the CONNECT command fails.

See Also:

Your operating system specific Oracle documentation for information about creating the OSDBA and OSOPER groups

Using Password File Authentication

This section describes how to authenticate an administrative user using password file authentication.

Preparing to Use Password File Authentication

To enable authentication of an administrative user using password file authentication you must do the following:

Create an operating system account for the user.

If not already created, create the password file using the ORAPWD utility:

ORAPWD FILE=filename PASSWORD=password ENTRIES=max_users

Set the REMOTE_LOGIN_PASSWORDFILE initialization parameter to EXCLUSIVE.

Connect to the database as user SYS (or as another user with the administrative privileges).

If the user does not already exist in the database, create the user. Grant the SYSDBA or SYSOPER system privilege to the user:

GRANT SYSDBA to oe;

This statement adds the user to the password file, thereby enabling connection ASSYSDBA.

Connecting Using Password File Authentication

Administrative users can be connected and authenticated to a local or remote database by using the SQL*Plus CONNECT command. They must connect using their username and password and the AS SYSDBA or AS SYSOPER clause. For example, user oe has been granted the SYSDBA privilege, so oe can connect as follows:

CONNECT oe/oe AS SYSDBA

However, user oe has not been granted the SYSOPER privilege, so the following command will fail:

CONNECT oe/oe AS SYSOPER

Note:

Operating system authentication takes precedence over password file authentication. Specifically, if you are a member of the OSDBA or OSOPER group for the operating system, and you connect as SYSDBA or SYSOPER, you will be connected with associated administrative privileges regardless of the username/password that you specify.

If you are not in the OSDBA or OSOPER groups, and you are not in the password file, then the connection will fail.

Using ORAPWD

When you invoke this password file creation utility without supplying any parameters, you receive a message indicating the proper use of the command as shown in the following sample output:

orapwd
Usage: orapwd file=<fname> password=<password> entries=<users>
where
file - name of password file (mand),
password - password for SYS (mand),
entries - maximum number of distinct DBAs and OPERs (opt),
There are no spaces around the equal-to (=) character.

The following command creates a password file named acct.pwd that allows up to 30 privileged users with different passwords. In this example, the file is initially created with the password secret for users connecting as SYS.

orapwd FILE=acct.pwd PASSWORD=secret ENTRIES=30

The parameters in the ORAPWD utility are described in the sections that follow.

FILE

This parameter sets the name of the password file being created. You must specify the full path name for the file. The contents of this file are encrypted, and the file cannot be read directly. This parameter is mandatory.

The types of filenames allowed for the password file are operating system specific. Some operating systems require the password file to adhere to a specific format and be located in a specific directory. Other operating systems allow the use of environment variables to specify the name and location of the password file. See your operating system documentation for the names and locations allowed on your platform.

If you are running multiple instances of Oracle Database using Oracle Real Application Clusters, the environment variable for each instance should point to the same password file.

Caution:

It is critically important to the security of your system that you protect your password file and the environment variables that identify the location of the password file. Any user with access to these could potentially compromise the security of the connection.

PASSWORD

This parameter sets the password for user SYS. If you issue the ALTER USER statement to change the password for SYS after connecting to the database, both the password stored in the data dictionary and the password stored in the password file are updated. This parameter is mandatory.

Note:

You cannot change the password for SYS if REMOTE_LOGON_PASSWORDFILE is set to SHARED. An error message is issued if you attempt to do so.

ENTRIES

This parameter specifies the number of entries that you require the password file to accept. This number corresponds to the number of distinct users allowed to connect to the database as SYSDBA or SYSOPER. The actual number of allowable entries can be higher than the number of users, because the ORAPWD utility continues to assign password entries until an operating system block is filled. For example, if your operating system block size is 512 bytes, it holds four password entries. The number of password entries allocated is always a multiple of four.

Entries can be reused as users are added to and removed from the password file. If you intend to specify REMOTE_LOGON_PASSWORDFILE=EXCLUSIVE, and to allow the granting of SYSDBA and SYSOPER privileges to users, this parameter is required.

Caution:

When you exceed the allocated number of password entries, you must create a new password file. To avoid this necessity, allocate a number of entries that is larger than you think you will ever need.

Setting REMOTE_LOGIN_ PASSWORDFILE

In addition to creating the password file, you must also set the initialization parameter REMOTE_LOGIN_PASSWORDFILE to the appropriate value. The values recognized are:

NONE: Setting this parameter to NONE causes Oracle Database to behave as if the password file does not exist. That is, no privileged connections are allowed over nonsecure connections. NONE is the default value for this parameter.

EXCLUSIVE: An EXCLUSIVE password file can be used with only one database. Only an EXCLUSIVE file can contain the names of users other than SYS. Using an EXCLUSIVE password file lets you grant SYSDBA and SYSOPER system privileges to individual users and have them connect as themselves.

SHARED: A SHARED password file can be used by multiple databases running on the same server. However, the only user recognized by a SHARED password file is SYS. You cannot add users to a SHARED password file. All users needing SYSDBA or SYSOPER system privileges must connect using the same name, SYS, and password. This option is useful if you have a single DBA administering multiple databases.

Suggestion:

To achieve the greatest level of security, you should set the REMOTE_LOGIN_PASSWORDFILE initialization parameter to EXCLUSIVE immediately after creating the password file.

Adding Users to a Password File

When you grant SYSDBA or SYSOPER privileges to a user, that user's name and privilege information are added to the password file. If the server does not have an EXCLUSIVE password file (that is, if the initialization parameter REMOTE_LOGIN_PASSWORDFILE is NONE or SHARED) Oracle Database issue an error if you attempt to grant these privileges.

A user's name remains in the password file only as long as that user has at least one of these two privileges. If you revoke both of these privileges, Oracle Database removes the user from the password file.

Creating a Password File and Adding New Users to It

Use the following procedure to create a password and add new users to it:

Follow the instructions for creating a password file as explained in "Using ORAPWD".

Set the REMOTE_LOGIN_PASSWORDFILE initialization parameter to EXCLUSIVE.

Connect with SYSDBA privileges as shown in the following example:

CONNECT SYS/password AS SYSDBA

Start up the instance and create the database if necessary, or mount and open an existing database.

Granting the SYSDBA or SYSOPER privilege to a user causes that user's username to be added to the password file. This enables the user to connect to the database as SYSDBA or SYSOPER by specifying username and password (instead of using SYS). The use of a password file does not prevent operating system authenticated users from connecting if they meet the criteria for operating system authentication.

Granting and Revoking SYSDBA and SYSOPER Privileges

If your server is using an EXCLUSIVE password file, use the GRANT statement to grant the SYSDBA or SYSOPER system privilege to a user, as shown in the following example:

GRANT SYSDBA TO oe;

Use the REVOKE statement to revoke the SYSDBA or SYSOPER system privilege from a user, as shown in the following example:

REVOKE SYSDBA FROM oe;

Because SYSDBA and SYSOPER are the most powerful database privileges, the WITH ADMIN OPTION is not used in the GRANT statement. That is, the grantee cannot in turn grant the SYSDBA or SYSOPER privilege to another user. Only a user currently connected as SYSDBA can grant or revoke another user's SYSDBA or SYSOPER system privileges. These privileges cannot be granted to roles, because roles are available only after database startup. Do not confuse the SYSDBA and SYSOPER database privileges with operating system roles.

Removing a Password File

If you determine that you no longer require a password file to authenticate users, you can delete the password file and reset the REMOTE_LOGIN_PASSWORDFILE initialization parameter to NONE. After you remove this file, only those users who can be authenticated by the operating system can perform database administration operations.

Caution:

Do not remove or modify the password file if you have a database or instance mounted using REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE (or SHARED). If you do, you will be unable to reconnect remotely using the password file. Even if you replace it, you cannot use the new password file, because the timestamps and checksums will be wrong.

Changing the Password File State

The password file state is stored in the password file. When you first create a password file, its default state is SHARED. You can change the state of the password file by setting the initialization parameter REMOTE_LOGIN_PASSWORDFILE. When you start up an instance, Oracle Database retrieves the value of this parameter from the parameter file used by the instance. When you mount the database, the database compares the value of this parameter to the value stored in the password file. If the values do not match, the database overwrites the value stored in the file.

Caution:

Ensure that an EXCLUSIVE password file is not accidentally changed to SHARED. If you plan to allow instance startup from multiple clients, each of those clients must have an initialization parameter file, and the value of the parameter REMOTE_LOGIN_PASSWORDFILE must be the same in each of these files. Otherwise, the state of the password file could change depending upon where the instance was started.

Server Manageability

Oracle Database is a sophisticated self-managing database that automatically monitors, adapts, and repairs itself. It automates routine DBA tasks and reduces the complexity of space, memory, and resource administration. Several advisors are provided to help you analyze specific objects. The advisors report on a variety of aspects of the object and describe recommended actions. Oracle Database proactively sends alerts when a problem is anticipated or when any of the user-selected metrics.

In addition to its self-managing features, Oracle Database provides utilities to help you move data in and out of the database.

Automatic Manageability Features

Oracle Database has a self-management infrastructure that allows the database to learn about itself and use this information to adapt to workload variations and to automatically remedy any potential problem. This section discusses the automatic manageability features of Oracle Database.

Automatic Workload Repository

Automatic Workload Repository (AWR) is a built-in repository in every Oracle Database. At regular intervals, the database makes a snapshot of all its vital statistics and workload information and stores them in AWR. By default, the snapshots are made every 30 minutes, but you can change this frequency. The snapshots are stored in the AWR for a period of time (seven days by default) after which they are automatically purged.

Automatic Maintenance Tasks

Oracle Database uses the information stored in AWR to identify the need to perform routine maintenance tasks, such as optimizer statistics refresh and rebuilding indexes. Then the database uses the Scheduler to run such tasks in a predefined maintenance window.

Server-Generated Alerts

Some problems cannot be resolved automatically and require the database administrator's attention. For these problems, such as space shortage, Oracle Database provides server-generated alerts to notify you when then problem arises. The alerts also provide recommendations on how to resolve the problem.

Advisors

Oracle Database provides advisors to help you optimize a number of subsystems in the database. An advisory framework ensures consistency in the way in which advisors are invoked and results are reported. The advisors are use primarily by the database to optimize its own performance. However, they can also be invoked by administrators to get more insight into the functioning of a particular subcomponent.

SQL*Loader

SQL*Loader is used both by database administrators and by other users of Oracle Database. It loads data from standard operating system files (such as, files in text or C data format) into database tables.

Export and Import Utilities

Oracle export and import utilities enable you to move existing data in Oracle format between one Oracle Database and another. For example, export files can archive database data or move data among different databases that run on the same or different operating systems.